Unfortunately shipping settings regarding which destinations are allowed are set on an account-wide basis so single items can't be excluded from the settings that apply to the others.
What we usually recommend in this scenario is to put a warning on your site that any international orders for that item will be canceled and refunded since you can't ship it. As a backup measure it is possible to program in an unreasonably high shipping cost for that one specific item to make buyers think twice about trying to checkout.
I've looked over your account's shipping settings and it would be possible to add that kind of cost without disturbing your original settings but it would take a bit of work. You'd have to rewrite your non-US shipping rules and then delete the originals.
I've prepared a set of instructions specific to your account to help with that if you'd like to make this change, but if it seems too unwieldy to enter you can still get effective results by just adding a warning to your website:
On the screen at Seller Admin > Shipping Calculation you can scroll to the bottom and see a menu for your existing shipping rules. It looks like your account has several varying flat rates set up based on the number of items ordered and their destination. You have four different rates for the US, Canada and then All other outside countries. The menu will list which country is involved as US, CA or All, start by writing down the rule numbers for the entries that have CA and All so that you can refer to them and erase them later.
The new versions of these rules should be the same with the exception of a strict weight limit. Here's an example of the new settings for one of your Canadian rules (any settings not specifically mentioned can be ignored):
Shipping Calculation: Flat Rate Per Order
Flat Shipping Amount: 12.00
Destination Country: Canada
- check the box for Order Size Requirements
Item Quantity Min: 1
Item Quantity Max: 3
Total Weight Min: 0
Total Weight Max: 0.9
Since your products all have weight values of 0 they'd still fall into these requirements and keep working as normal. This rule would charge 12.00 for orders of 1 to 3 items in Canada and exclude your special item.
You'll need to repeat the settings above to recreate the other rules for Canada and International ("all"). The values to use can be seen in the menu that summarizes your existing shipping rules. You can create a rule that is "21 or more" items by setting Item Quantity Min to 21 and Max to 0 (zero means no upper limit).
With those entered you can delete the old ones safely. Your existing US rules do not need to be altered at all because they already accept any weight range.
Next you just need one new rule that will catch any order for this special item that isn't going to the US. Use the following settings:
Calculation Method: Flat rate per order
Flat Shipping amount: 9999.99
Destination Country: All Countries
-check the box for Order Size Requirements and add
Min Item Weight: 1
Max Item Weight: 0
That would add a huge cost to any attempt to order something over "one ounce" outside of the US.
Finally, the very last step would be to go to Seller Admin > View/Edit/Delete Items and edit the item you want to exclude from international shipping. Set that item to weigh 1 or more ounces and this setup will be complete.
